In Brief: Martian soil oxidation-reduction potential not too extreme for life

Aug 18, 2011

Ever since the NASA Viking mission, which reached Mars in 1976, there has been considerable interest in the composition of Martian soils.

Some Viking measurements indirectly suggested that the soils contained highly oxidizing compounds, which could present extremely harsh conditions for life.

Recent observations from the Phoenix Mars Mission pointed to evidence of , a potentially highly oxidizing compound, in the Martian soils. However, some studies have noted that because perchlorate is highly stable, its presence in Martian soils cannot explain the Viking measurements.

Quinn et al. present a new analysis of Mars using the Wet Chemistry Laboratory, a component of the Microscopy, Electrochemistry, and Conductivity Analyzer on the NASA . They find that although low levels of oxidizing compounds may be present, the oxidation-reduction potential of the soil is moderate and well within the range expected for habitable soils.

Explore further: Space sex geckos at risk as Russia loses control of satellite

More information: Quinn, R. C., J. D. Chittenden, S. P. Kounaves, and M. H. Hecht (2011), The oxidation-reduction potential of aqueous soil solutions at the Mars Phoenix landing site, Geophys. Res. Lett., 38, L14202, doi:10.1029/2011GL047671

Abstract
Results from the Mars Phoenix mission Wet Chemistry Laboratory (WCL) are used to determine the oxidation-reduction potential (Eh) of the Phoenix WCL Rosy Red sample soil solution. The measured Eh of the Rosy Red sample in the WCL aqueous test solution was 253 ± 6 mV at a pH of 7.7 ± 0.1. Measured solution Eh changes correspond to changes in solution H+ activity, which is controlled mainly by changes in headspace PCO2 and solution CO32−, HCO3−, and CO2 concentrations. If measured at a PCO2 of 8 mbar in water, rather than in WCL test solution, the Eh of the Rosy Red soil solution would be ∼300 mV. The results of laboratory experiments using analog salt mixtures are compatible with the possible presence of low levels (ppm) of metal peroxides or other oxidants and indicate that levels of readily soluble ferrous iron in the soil are below 1 ppm.

add to favorites email to friend print save as pdf

Related Stories

Viking landers did detect organics on Mars

Jan 06, 2011

(PhysOrg.com) -- In 1976 the NASA Viking landers took samples of soil on Mars and tested them for signs of organic carbon. A reinterpretation of the results now suggests the samples did contain organic compounds, ...

Missing piece inspires new look at Mars puzzle

Sep 03, 2010

(PhysOrg.com) -- Experiments prompted by a 2008 surprise from NASA's Phoenix Mars Lander suggest that soil examined by NASA's Viking Mars landers in 1976 may have contained carbon-based chemical building blocks ...

Recommended for you

Video: A dizzying view of the Earth from space

18 hours ago

We've got vertigo watching this video, but in a good way! This is a sped-up view of Earth from the International Space Station from the Cupola, a wraparound window that is usually used for cargo ship berthings ...

NEOWISE spots a comet that looked like an asteroid

18 hours ago

Comet C/2013 UQ4 (Catalina) has been observed by NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) spacecraft just one day after passing through its closest approach to the sun. The comet ...

What the UK Space Agency can teach Australia

18 hours ago

Australia has had an active civil space program since 1947 but has much to learn if it is to capture a bigger share of growing billion dollar global space industry. ...

Discover the "X-factor" of NASA's Webb telescope

18 hours ago

NASA's James Webb Space Telescope and Chandra X-ray observatory have something in common: a huge test chamber used to simulate the hazards of space and the distant glow of starlight. Viewers can learn about ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

deatopmg
1 / 5 (1) Aug 19, 2011
This result suggests that neither perchlorate nor metal peroxides can be the proposed magical mystery oxidizer NASA implies caused one of the 1976 Viking's life detection experiments to give continuing, diurnaly variable, positive results over ca. 45 days. So, it appears Viking really did detect life

And, supposedly, no new life detection systems have been sent to Mars for 35 yrs. Why not?